In vitro antiviral activity of chitosan and curcumin-loaded chitosan nanoparticles against virulent Newcastle disease virus isolates.

Abstract

Newcastle disease virus (NDV) is a highly contagious avian pathogen requiring effective antiviral strategies. This study evaluated the in vitro antiviral efficacy of chitosan nanoparticles (CNPs) and curcumin-loaded chitosan nanoparticles (Cur-CNPs) against virulent NDV isolates from poultry in Kerala, India. Screening of 40 suspected flocks by reverse transcription polymerase chain reaction (RT-PCR) targeting the fusion (F) gene revealed a 12.5&#xa0;% positivity rate. Sequencing confirmed virulent strains based on amino acid motifs at the F protein cleavage site. Two isolates, L2/MIB/PKD/23 and B3/MIB/PKD/23, were propagated in embryonated chicken eggs, and their virulence was confirmed through hemagglutination, hemagglutination inhibition, and mean death time assays. Virus adaptation to cell culture demonstrated higher replication efficiency in chicken embryo fibroblast cells. CNPs and Cur-CNPs were synthesised via ionic gelation and characterized by spectroscopic and microscopic techniques. Cytotoxicity assessment determined minimum non-cytotoxic concentrations of 187.5&#xa0;&#x3bc;g/mL for CNPs and 1.47&#xa0;&#x3bc;g/mL for Cur-CNPs. Antiviral activity, evaluated by MTT assay, demonstrated the highest protection with Cur-CNPs (0.75:1 ratio), achieving 44.18&#xa0;% and 47.12&#xa0;% protection for the two isolates. Viral titre reduction assays indicated a decrease of 3.00 log10 in TCID50 and a twofold reduction in hemagglutination titres. Quantitative real-time PCR confirmed significant viral load reductions (p&#xa0;<&#xa0;0.001) with Cur-CNPs compared to CNPs. These findings indicate that Cur-CNPs exhibit strong antiviral activity against NDV and may serve as potential alternatives to conventional antiviral agents for Newcastle disease control.